Concrete for road covering



H0 u 6 e n Per )f /AMJUJ Attorney.

v f5 n M AND PAvEMEm-e UNITED STATES xaminor PATENT OFFICE.

CONCRETE FOB BOAID COVEBING.

Specification of Letters Patent.

Patented Mar. 28, 1922.

Application led September 18, 1919. Serial No. 324,554.

(GRANTED UNDER THE PROVISIONS 0F THE ACT 0F IABCH 3, 1921, 41 STAT. L., 1313.)

To all whom it may con/cem Be it known that I, ROBERT HOUBEN, a. citizen of the Kingdom of Belgium` residing at Uccle, Belgium, have invented new and useful Improvements in Concrete for Road Covering, (for which I have filed applications as follows: Belgium, Nov. 19, 1913, and June 27, 1914; France, Dec. 31, 1913. and June 29, 1914; Great Britain, Feb. 19, 1914, Patent No. 4349 of 1914; Germany, Nov. 27, 1913; Holland, Nov. 27. 1913; Norway and Denmark, Mar. 30, 1914; Canada. Apr. 7, 1914, and Australia, Apr. 29, 1914,) of which the following is a specification.

This invention has for its object the manufacture of a concrete suitable for covering roads and which for this purpose is waterproofed and made suliciently elastic to allow the mass to expand and contract under the action of variations of temperature without cracking.

Concrete manufactured according to this invention can also be used with advantage for makin moulded articles and for all pur oses or which concrete is generally use It has already been proposed to waterproof concrete and render the same elastic by embodying therein fibrous materials such as paper or sawdust impregnated with oils, tars, resin, glues or other viscid materials but the process does not appear to have been carried into practice for the covering of roads the reason being presumably that neither suitable proportions of the materials nor the manner in which the ingredients should be mixed together for obtaining suiiiciently resisting concrete had yet been determined.

According to my invention excellent results have been obtained by mixing with the usual components of concrete a small percentage of a powdered fibrous material impregnated with a waterproofing substance the proportions being such that the concrete does not lose its nature and inherent roperties. My invention consists also in t e manner of preparing the waterproofing material so as to avoid agglutination of the particles of fibrous material which often precludes an even distribution of the said particles within the concrete.

Two embodiments of the invention are illustrated by way of example in the a9- companying drawing, in which Fi s. 1 and 2 .show cross-sections of roads ma e according to my improved method.

In Fig. 1, 1 is a layer of my improved concrete of a thickness of 10 centimeters, and 2 is a 15 centimeter foundation of concrete containing from 17 5 to 200 kilograms of cement per cubic meter of broken stone and sand.

In Fig. 2, 3 is a 10 centimeter layer of my improved concrete, and 4 a foundation made of sand stones placed on edge and rammed.

In carrying my invention into practice I prepare the waterproofing material by heating and mixing together tar and bitumen in a stirring device heated to between 100 and 130 C.

The mixture of tar and bitumen is then poured onto and thoroughly mixed with sawdust powdered cork or the like in another stirring device which is also preferably heated. The mixture of tar and bitumen is quickly absorbed by the fibrous material which after being allowed to cool and dry remains in the form of a powder.

On the other hand concrete is prepared of cement, sand, broken stones and water in the usual proportions and the impre ated fibrous material is thoroughly mix with the wet concrete without further addition of water.

By way of example, for obtaining a cubic metre of elastic waterproof concrete suitable or covering a road adapted to undergo a heavy traic the following proportions should preferably be used:

Cement from 400 to 500 kg., sand about 600 kg., broken stones about 1200 kg.

With these materials is mixed a suitable uantity of water, which depends on the degree of moisture of the sand and of the broken stones. To the resulting mixture are then added about 14 kg. of impregnated fibrous material comprisirg 8 kg. of sawdust or pulverized cork or the l e and 6 kg. of tar mixed with about 120 grammes of asphaltic rock bitumen.

If the road is intended to undergo only a light trailic the percentage of impregnated brous material can be increased.

The addition of bitumen to the tar has the effect of xing the tar into the fibrous particles and preventing the latter from sticki Msn:

ing to ether so that after the same have been allowed to dry they remain in a state of perfect division.

Having thus fully described my invention what I claim is:

1. Concrete for road coverings consisting of cement, sand and broken stones mixed together with water in the usual proportions and from 0.5 to 2 per cent by weight of powdered fibrous material impregnated with a mixture of tar and bitumen.

2. Concrete for road coverings consisting of cement, sand and broken stones mixed together with water in the usual proportions and about 0.7 per cent by weight. of sawdust impregnated with a mixture consisting of 100 parts by weight of tar and about 2 parts by weight of asphaltic rock bitumen.

3. Process for the manufacture of a concrete for road coverings which consists in melting and mixing together tar and bitumen impregnating saw ust with the resulting mixture and mixing from 0.5 to 2 per cent of said impregnated sawdust with cement sand and broken stones mixed together with water in conventional proportions.

4. Process for the manufacture of concrete for road coverings which consists in mixing together about 400 kg. of cement, 600 kg. of sand, 1200 kg. of broken stones with the usual proportion of water and adding and mixing therewith about 14 kg. of impregnated fibrous material comprising 8 kg. of sawdust, 6 kg. of tar and about 120 gr. of asphaltic rock bitumen.

In testlmony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

ROBERT HOUBEN.

Witnesses:

LEON PIRARD, M. V. KIR'KPATRICK. 

